I’ve found this problem exists (even though it’s worse with confluence) no matter what you use, and the solution is a better hierarchy
We have a pretty substantial Confluence Cloud and don't see the "search doesn't work" problem. Tangent: we have people who browse, and people who search, and ne'er the twain shall meet, but that's a different problem in page structure, conventions, tags, whatever.
My experience with _every_ knowledge base has been that this is the solution. My current team has confluence pages pinned to slack channels which link to the other necessary pages.
But, my experience is that even when search is good, you need the right query. Take onboarding instructions. Do you search for "new hire", "initial setup", "setup guide", "engineering onboarding", "programmer first steps"?
Or, do you send a link in a welcome email to the right page, and have it pinned on the home page of your project?
Honestly, I think confluence would be better _without_ search.